Bialas, Jörg

Böttner, Christoph

Carey, Jon

Crutchley, Gareth

Dannowski, Anke

Gross, Felix

Huhn, Katrin

Koch, Stephanie

Krastel, Sebastian

Micallef, Aaron

Mountjoy, Joshu

Pecher, Ingo

Woelz, Susanne

OceanRep

Geophysical Research AbstractsVol. 18, EGU2016-2078, 2016EGU General Assembly 2016© Author(s) 2016. CC Attribution 3.0 License.Submarine creeping landslide deformation controlled by the presence ofgas hydrates: The Tuaheni Landslide Complex, New ZealandFelix Gross (1), Joshu Mountjoy (2), Garethy Crutchle (3), Stephanie Koch (4), Jörg Bialas (4), Ingo Pecher (5),Susi Woelz (2), Anke Dannowski (4), Jon Carey (3), Aaron Micallef (6), Christoph Böttner (1), Katrin Huhn (7),and Sebastian Krastel (1)(1) Christian-Albrechts-Universität zu Kiel, Institute of Geosciences, Geophysics, Kiel, Germany(fgross@geophysik.uni-kiel.de), (2) NIWA, Wellington, New Zealand, (3) GNS Science, Lower Hutt, New Zealand, (4)GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany, (5) University of Auckland, Faculty of Science, Auckland,(6) University of Malta, Msida, Malta, (7) Marum, Bremen, GermanyMethane hydrate occurrence is bound to a finite pressure/temperature window on continental slopes, known as thegas hydrate stability zone (GHSZ). Hydrates within sediment pore spaces and fractures are recognized to act likea cement, increasing shear strength and stabilizing slopes.However, recent studies show that over longer strain periods methane hydrates can undergo ductile deformation.This combination of short term strengthening and longer term ductile behavior is implicated in the developmentof slow creeping submarine landforms within the GHSZ.In order to study this phenomenon, a new high-resolution seismic 3D volume was acquired at the TuaheniLandslide Complex (TLC) at the Hikurangi margin offshore the North Island of New Zealand. Parts of TLC havebeen interpreted as a slow moving landslide controlled by the gas hydrate system. Two hypotheses for its slowdeformation related to the presence of methane hydrates have been proposed: i) Hydrofracturing, driven by gaspressure at the base of the GHSZ, allows pressurized fluids to ascend toward the seafloor, thereby weakening theshallow debris and promoting failure. ii) The mixture of methane hydrates and sediment results in a rheology thatbehaves in a ductile way under sustained loading, resulting in slow deformation comparable to that of terrestrialand extra-terrestrial rock glaciers.The 3D dataset reveals the distribution of gas and the extend of gas hydrate stability within the deformed debris, aswell as deformation fabrics like tectonic-style faulting and a prominent basal décollement, known to be a criticalelement of terrestrial earth-flows and rock glaciers. Observations from 3D data indicate that the TLC representsthe type example of a new submarine landform – an active creeping submarine landslide – which is influenced bythe presence of gas hydrates. The morphology, internal structure and deformation of the landslide are comparablewith terrestrial- and extra-terrestrial earth flows and rock-glaciers.

Submarine creeping landslide deformation controlled by the presence of gas hydrates: The Tuaheni Landslide Complex, New Zealand

Submarine creeping landslide deformation controlled by the presence of gas hydrates: The Tuaheni Landslide Complex, New Zealand

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